Known image forming apparatuses include a lower casing, and an upper casing serving as a top cover. The lower casing includes a photosensitive drum. The top cover has a first end which is supported such that the top cover is pivotable on a predetermined axis relative to the lower casing. The top cover is capable of opening and closing relative to the lower casing.
In some of the known image forming apparatuses, a photosensitive drum and a cartridge containing toner are attached to the lower casing, and an LED array that is an exposure unit for exposing the photosensitive drum is disposed at its top cover.